For most people, their web browser is central to their interaction with the Internet, connecting to global web sites and helping them consume online services providing everything from booking flights to banking services to online shopping. This reality makes browsers a key tool when evaluating the security experience of users as the browser interprets Web content and programs delivered from around the world.

Over the past few years, there has been much discussion of the need for improvements in browser security, but few hard data studies performed to support assertions concerning the security of available browsers.

This report documents the results of my analysis of Internet Explorer and Firefox vulnerabilities over the past few years since Internet Explorer 6 on Windows XP SP2 became available and Mozilla launched Firefox.

The report in detail examines vulnerabilities over the past 3 years, breaks them down by severity, looks at version-over-version trends for each browser and finally examines how each browser is doing in terms of unfixed vulnerabilities.